The life-insurance company of a Long Island motivational speaker slain in a suicidal murder-for-hire plot is trying to block his wife from collecting on his $4 million policy.

Principal Group Life Insurance claims in a lawsuit filed yesterday in Brooklyn federal court that Jeffrey Locker, 52, lied about his income on a policy he took out a month before his death — making the agreement void.

Locker, who was swimming in debt at the time of his murder on June 4, 2009, allegedly paid an East Harlem man, Kenneth Minor, $1,000 to “do a Kevorkian” on him.

Prosecutors believe the tale and even reduced Minor’s charges to second-degree murder.

Locker claimed to be making $800,000 from his motivational-speaking business, the Locker Group, and reported his net worth at $6 million, according to the insurance company’s claim.

But he told his murderer that he lost $400,000 in a Ponzi scheme.

Locker also was being sued in Florida bankruptcy court for money that he allegedly made in a Ponzi scheme run by Lou Pearlman, the former manager of the Backstreet Boys.